Cyanobacteria are an alternative to reduce chemical fertilization and increase production in crops of commercial interest. Cyanobacteria have the ability to fixation N, produce growth regulators, vitamins and amino acids with the ability to stimulate plant growth. The objective of this project was to determine the effect of the inoculation of cyanobacteria isolated from Guajira rice crops on rice, maize and bean plants. Six rice farm were sampled in the municipalities of Fonseca and Distracción. Three integrated samples of substrate scraping and surface water were obtained from each farm. The microalgae were isolated in BG11 medium and identified morphologically. The cyanobacteria Gloeocapsa and Oscillatoria amphibia, individually and in mixture, were inoculated in rice, bean and maize plants in experimental plots. Non-inoculated plants were used as negative control, as well as plants with chemical fertilization. A daily record was made of plant height. It was identified 15 genera of microalgae such as Gloeocapsa sp., Chlorella sp., Scenedesmus sp., Anabaena sp., Chrococcus sp., and Oscillatoria among others. The inoculation with the cyanobacteria did not present significant differences with respect to the nitrogen fertilization in the three crops, which represents a saving in fertilization. From the 35 days inoculation the treatment with Gloeocapsa sp presented significant increases with respect to the control without inoculating up to 15.0% in rice plants. These results postulate Gloeocapsa as a potential biofertilizer for rice crops and the inoculation of cyanobacteria as a substitute for nitrogen fertilization in crops such as corn and beans.